Discussion

A look back at January
January has featured well below-normal temperatures in the Mid-Atlantic region along with above-normal snowfall in most areas; especially, north of the PA/MD border. Specifically, temperatures through Tuesday, January 28th were 4.2 degrees below-normal at Philly Intl Airport, 3.4 below-normal in Central Park, New York City, and 3.2 degrees below-normal at Reagan National Airport in Washington, DC. Snow-wise it has been a banner month in much of the Mid-Atlantic region north of the PA/MD border. Philadelphia, for example, has received 24.9 inches of snow which ranks as the 4th snowiest January since 1872. Central Park, NY is also well above-normal for January with 18.9 inches of snow accumulation.

A look ahead to February
February looks like it’ll be a stormy and colder-than-normal month for the Mid-Atlantic region, but temperature departures from normal will likely not be as significant as they were in January. Snowfall should be above-normal for February as an active and stormy pattern will likely produce multiple snow threats in the region beginning as early as next week – the first full week of the new month. The core of the coldest air in terms of temperature departures from normal has been centered over the Upper Midwest/Great Lakes and that pattern should continue in February. As a consequence, the December-February time period could very well end up being in the “top ten coldest” for places like Chicago, Illinois by the time February is over.

Upper level differences and an "atmospheric battle zone"
One difference in the overall upper level pattern in February will likely be the re-establishment of the southeastern ridge of high pressure that was largely absent in January. This will probably result in warmer-than-normal temperatures in the Southeast US for the month and, given the expected continuing cold air across the northern US, it should set up quite an “atmospheric battle zone” with a large temperature gradient across the south-central US and an active southern branch of the jet stream. This "battle zone" between the increasingly warm air in the Southeast US and the lingering cold across the northern tier of states should fuel some pretty strong storms during the month and lead to above-normal snowfall in the Mid-Atlantic region. An important aspect of the increasingly strong southeastern upper level ridge is that it will tend to "open the door" for Gulf of Mexico moisture to flow into the Mid-Atlantic region from the southwest.

NOAA temperature anomaly forecast map for February
Finally, one of NOAA’s longer-range computer forecast models (Climate Forecast System) is predicting a cold month for much of the nation (above) where “blues” represent below-normal temperature regions and “red/oranges” warmer-than-normal areas. This model has had a pretty good track record when close to event time and its forecast map represents quite well my thinking for the month of February with respect to nationwide temperature anomalies.